Online newspaper 'El Confidencial' reports that Deco, Samuel Eto'o and Ronaldinho were also subject to investigations by detectives, before Guardiola was coach.

Pep Guardiola allegedly hired a detective agency in order to spy on his players, according to the online newspaper 'El Confidencial'.

Gerard Piqué was reported to be the player that the firm 'Método 3' followed the most, but Ronaldinho, Deco and Samuel Eto'o are also believed to have been the subject of investigations, before Guardiola became the club's coach.

Guardiola would even make calls to his players' houses to ensure they were at home and not out on the town, sources close to Barça players told the newspaper.

"He was obsessed with the idea that his players had quiet private lives and did not go out drinking, because afterwards they would not perform on the pitch," states the report, quoting a former Barcelona employee.

Guardiola used the services of detectives during the early hours of the morning, in case they discovered that one of the players had organised a night out with friends, and asked the services to send someone there immediately.

While spying on Piqué, the detectives found out that his favourite bar was a cocktail bar near the club's training ground, and even gave details of the drinks he ordered.

They also revealed he was once stopped by police on the way home from a concert and was subject to a drink driving test, which came out negative.